[VP] Preserve address space of pointer for strided load/store intrinsics.

This adds LLVMAnyPointerToElt to use instead of LLVMPointerToElt.
This allows us to preserve the address space as part of the type
overload for the intrinsic, but still require the vector element
type to match the pointer type.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D122042